Piston



P. e. VVANNI Jan. 9, 1934 PISTON Filed Oct. 6. 1931 ,P C V IN VENTOR W IKWZQB *C'aw-kbzll A TTORNE V8,

Patented Jan. 9, 1934 PATENT OFFICE 1,942,887 PISTON Pier Giorgio Vanni,Milan, Italy Application October 6, 1931, Serial No. 567,188, and inGermany March 9, 1931 9.Claims.

This invention relates to pistons, and more especially to pistons of thetrunk type, such as are adapted for use in the internal combustionengines, although the utility of the invention is not confined thereto.

The general object of the invention is to afford a more efiective anddurable piston. A particular object is to afford a piston wherein thebarrel or shell and the crown are of quite light constructions andwhich, nevertheless, will not deform under working conditions; in otherwords a piston which is light, strong and rigid. A further object is toprovide in a pistonof the kind referred to an effective system ofcooling the piston crown and shell. Other andfurther objects of theinvention will be explained in the hereinafter following description ofillustrative, embodiments thereof-or will be understood by thoseconversant with the subject. To the accomplishment of the aforesaidobjects and advantages the present invention consists in the novelpiston, and the novel features of construction and combination hereinillustrated or described.

In the'accompanying drawing Fig. 1 is a central longitudinal section ofa piston embodying the present invention.

Fig. 2 is a bottom plan view of Fig. 1 with the connecting rod omitted.

Figs. 3 and 4 are perspective views of certain of the interior partsdisassembled.

Fig. 5 is a perspective elevation of the interior parts of a modifiedform of the invention.

According to the present invention the piston, with its thin outer shelland crown, and the wrist pin. on which the connecting rod oscillates andwhich is supported and spaced within the shell, are combined with aninterior element or structure in the nature of a frame or shell formedwith an upper peripheral or base that contacts and supports the crown ofthe piston and sides or walls that converge downwardly and at the vertexa lower central portion abutting or supported upon the wrist pin. Theassembled parts 45 after being inserted within the piston shell arethere suitably and permanentlyconfined, and a structure results havingcertain of the advantages already described; these same parts beingformed with oil conducting passages so as. continually to feed oil tothe inner sides of the piston crown and shell, thus aifording the pistoncooling function described.

The main shell, barrel or cylindrical portion 11 of the piston may becomposed of thin cast metal. It is shown as extended downwardly in theform of an extra thin skirt 12. The top or head end of the piston isclosed by a crown or plate 13 also thin and cast integrally with theshell 11.

Near the interior center of the piston is shown the usual wrist orgudgeon pin 15. This may be 50 cut away at its top side to form a recess16, below which the pin may have a vertical bore 1'7, from the bottom ofwhich an oil passage 18 extends downwardly to the lower side of the pin.

The wrist pin may be supported in any suitable manner from the sides ofthe piston. Thus side pieces 19 are shown having circular aperturesreceiving the ends of the pin, and the side pieces are combined with andspaced apart by curved end pieces 20 fitting the interior of the shell.These elements 19 and 20 are confined within the piston by a ring 21threaded, wedged or otherwise fixed within the interior of the shell.

A connecting rod 22 is shown the upper end or head of which ispreferably divided by a recess into opposite sides or eyes 23 enclosingthe wrist pin, but the recess does not extend to the lower portion ofthe head, which thus gives lull support to the pin. The connecting rodmay be formed with a central oil passage 24 supplying oil for thelubrication of the pin.

The novel part of the structure comprises an interior frame, shell orwall 25, in the form of an inverted cone with its base 26 at its topperiphery, bearing against the crown of the piston. The sides of theshell 25 converge or taper downwardly toward a lower portion or base 2'7which rests within the recess 16 of the gudgeon pin and which may beextended in the form of a cylinder 28 depending in the bore 17.

The walled structure 25 encloses a chamber 29 below the piston crown.The structure may comprise also a central column 30 also in abuttingcontact with the piston crown and supporting the central part thereof. I

To enable the flow of lubricating oil to be used as a cooling mediumthere is shown an oil passage 31 extending through the parts 28, 2'1,and 30 in line with the oil passage 18 in the gudgeon pm. This permitsascending oil to reach the 1 top of the hollow column 30, from which itmay fiow by exit apertures 32 into the chamber 29,

from which in turn the oil "may pass by aper- 'tures 33 into the mainshell of the piston, the

oil thence flowing down the piston shell to be returned to the crankcase. In this way a continuous cooling of the piston is performed.

In Fig. 5 while the principles are the same the. structure is modifiedin several respects. The tapering wall 35 may be conical, with its upperperipheral base 36 pressing directly against the piston crown. Thecentral column .may be omitted. The lower end of the tapered wall may beintegrally connected with the parts that support the wrist pin. Thus anextension 3'1 constitutes a bearing for the pin, this bearing beingrecessed to accommodate the connecting rod. Flanged extensions 38 areshown at the lateral sides, their flanges adapted to contact theinterior .surface of the piston shell. When inserted in the shell thestructure of Fig. 5 may be secured in place by a confining ring similarto the ring 21 shown in Figs. 1 and 2. The wall 35 encloses a chamber 39which may receive oil from the wrist pin and discharge it upon the innersurface of the piston shell. The interior structure, readily receivesthe connecting rod and then the wrist pin, whereupon it may be bodilyinserted in the piston shell, thrust into firm contact with the crownand confined by the ring. After making of the single casting 35-38 theproper machining can be effected, including.

use of aluminum alloy.

It is understood that the external shell'll as well as the interiorstructure 35 38 could be made either by casting or by forging, ormachining a piece of metal. 1

An important consideration is that the interior parts of, this inventionare separately formed and thereafter inserted and locked or confinedwithin the piston. The interior structure, aside from the wrist pin mayeither comprise assembled parts mutually abutting each other between thecrown and the pin, as in Figs. 1 to 4, or they may be cast integrally asin Fig. 5. After assembling and insertion the parts may be confined invarious ways, for example by a part or ring 21 which may either beardirectly against an integral extension of the interior structure. as inFig. 5, or against a separate element or frame provided to space andsupport the wrist pin, as

in Figs. 1-4, in which case the wrist pin confines the interior partsabove it.

The interior frame or wall 25 while preferably closed to form a chamber,possesses an important function, not dependent on its closed character.This is due to the tapering form of the member extending from theperipheral rim 26 which supports the crown to a central vertex or part27 which is supported on the wrist pin. A bracing effect resultssuch aswould be given by a system of diagonal struts extending from the outerpart of the crown to the middle part of the pin, a very strong and rigidstructure. The rim of the member or wall 25 is preferably of such adiameterthat the perimetral tangent to the flexing sm'face of the crownis always horizontal whatever the gas pressure, so that the elasticdeforagainstsliding within the shell by the locking ring 21.

Various changes of form are possible while retaining the disclosedprinciples of structure, including the strut character of the element 2or 35 by which compression forces are well transmitted between the crownand pin. While Figs. 1 and 3 show central and peripheral support of thecrown they might be supplemented by additional walls or extensions, suchas concentric hollow cones contacting the crown. The pin could bechanged to oscillate with the rod rather than be held with the pistonstructure, the latter in such case supported by a bearing upon the pin.The piston shell interior could have turned ribs to strengthen it.

Since many disclosed matters of construction, arrangement and design maybe further variously modified without departing from the invention. itis not intended to limit the invention to such matters except so far asset forth in the appended claims.

What is claimed is:

1. A piston for internal combustion engines comprising a thin outershell with a crown closing its upper end, a transverse pin on which theconnecting rod oscillates, said pin being of such short length as not toreach to the thin piston shell but having means spacing it within thepiston shell, an inserted frame having an upper peripheral portionengaging the crown, sides tapering downwardly, and a lower, centralportion engaging the pin, and means confining the inserted parts withinthe shell.

2. A piston comprising a thin outer shell with a crown closing its upperend, a transverse pin on which the connecting rod oscillates, said pinbeing of such short length as not to reach to the thin piston shell buthaving means spacing it within the piston shell, an inserted framehaving an 110 upper peripheral portion supporting the crown, sidestapering downwardly, and a lower central portion engaging the pin, thepin being recessed at its upper side to receive the lower end of theframe.

3. -A piston comprising a thin outer shell with a crown closing itsupper end, a transverse pin on which the connecting rod oscillates, saidpin being of such short length as not-to reach to the thin piston shellbut having means spacing it within the piston shell, an inserted shellhaving an upper peripheral portion supporting the crown,

a wall tapering downwardly, and a lower central portion engaging thepin, the wall forming a chamber, passages conducting oil into the cham-125 her and peripheral passages from the chamber to the piston shell.

4. A piston comprising a thin outer shell with an integral crowncompletely closing its upper end, and a wrist pin, in combination with apreformed and inserted structure having (1) an upper peripheral portionsupporting the crown.

(2 sides tapering conically downward, (3) a lower central portionengaging the wrist pin, and

(4) an extension portion at the level of the pin for spacing thestructure and pin from the shell, all integral or united beforeinsertion, and means confining the inserted parts within the shell.

5. A piston -for internal combustion engines comprising a thin outershell with a crown closing its upper end, a transverse pin on which theconnecting rod oscillates, spaced within the piston shell, an insertedframe having an upper peripheral portion engaging the crown, sidestapering downwardly, and 'a lower central portion engaging the pin, andmeans confining the inserted parts within the shell; the insertedframehaving not only a peripheral portion but also a central columnabutting against the piston crown.

6., In a trunk piston a separately formed and 15c inserted structurehaving a peripheral extension abutting the piston crown and taperingtherefrom to"a central extension abutting the piston pin; the insertedstructure having not only a peripheral portionbut also a central columnabutting against the piston crown.

7. A piston comprising a thin outer shell with a crown closing its upperend, a transverse pin on which the connecting rod oscillates, spacedwithin the piston shell, an inserted frame having an upper peripheralportion engaging the crown, sides tapering downwardly, and a lowercentral portion engaging the;pin, the pin being recessed at its upperside to receive the lower end of the frame; the inserted frame havingnot only a peripheral portion but also a central columnlabutting againstthe piston crown.

8. A piston comprising a thin outer shell with a crown closing its upperend, a transverse pin on which the connecting rod oscillates, spacedwithin the piston shell, an inserted frame having an upper peripheralportion supporting the crown, a wall tapering downwardly, and a lowercentral portion engaging or supported on the pin, the

wall forming a chamber, the inserted frame from to a central extensionabutting the piston pin, the piston pin being formed with a top recessof substantial depth in which such central extension is engaged.

-PIER'GIORGIO VAN'NI.

